Vacuum discharge tube



' 1 644 601 1927' AP. HANS-GERD NICKEL ET AL VACUUM PISCHARGE TUBE Filed Feb 24. 1927 I 3 Fi .1.

l l l l M2 Alla in 42 Patented Oct. 4, 1927.

UNITED STATES PATENT OFFICE.

ALBERT PAUL HANS GERD NICKEL, OF CHARLOTTENBURG, AND JOHANNES JOACHIM SPANNER, OF BERLIN, GERMANY.

VACUUM DISCHARGE TUBE.

Application filed February 24, 1927, Serial No. 170,680, and in Germany September 9,1924.

()ur invention relates to improvements, in vacuum discharge tubes such for example as radio tubes, and the method of manufacturing the same. More particularly our invention relates to tubes of the type the wall of which is internally coated with metal. One of the objects of the improvements is toprovide a tube and a method of manufacturing the same, in which a part of the Wall is transparent while the main part thereof is coated with metal, so that the inner part of the tube can be inspected through the said transparent portion of the wall.

The invention is shown in the accompanying drawing, in which Fig. 1, is a sectional elevation showing our improved tube,

Fig. 2, is an elevation of the tube. I

As shown in Fig. 1 our improved tube consists of a glowing cathode 3, a grid 4 and a tubular anode 5, the said parts being connected with suitable terminals as is known in radio tubes. The portion 6 of the wall of the tube is provided internally with acoating of a suitable metal, which portion is opaque, while the portion 7 of the tube is transparent, so that the inner parts of the tube can be inspected throu h the portion 7. We wish it to be understoo that the transparent portion may be rovided at any suitable palt of the wall, t ough ordinarily we prfifer to provide the same at the top of the tu e.

The method of our invention, for providing the wall with a transparent portion, is as follows. We place a small thin plate 8 of a suitable material such as mica on the portion 7 of the wall while applying the metal coating 6. Therefore the said plate protects the part 7 from the metal being applied to the wall. It will be understood that when applying the'metal coating to the wall,

the tube is turned upside down. Thus when turning the tube after coating the wall thereof. the plate drops from the portion 7, and it is left at a part of the tube where it does not interfere with the operation. In Fig. 1 we have shown the plate at the left hand bottom part of the tube.

By providing a plate of a suitable material. such for example as mica, graphite, etc., the said protective plate is adaptedto absorb a portion of the gas, such as hydrogen, used for filling the tube, so that after partial evacuation of the tube andconsumption of the hydrogen in the course of the operation thereof, the said hydrogen is regenerated from the mica plate.

We claim:

1. The herein described method of coating vacuum discharge tubes with metal, which consists in loosely placing a. protective plate on a portion of the wall of the tube, precipitating metal contained within the tube, and reinoving said plate from the wallet the tu e.

2. The herein described method of coatin vacuum discharge tubes with metal, whic consists in loosely placing a protective plate adapted to absorb gas on a portion of the wall of the tube, precipitating metal contained within the tube, and removing said plate from the Wall of the tube.

3. The herein described method of coating vacuum discharge tubes with metal, which consists in, loosely placing a protective plate of mica on a portion of the wall of the tube, precipitating metal contained within 1 the tube. and removing said plate from the wall of the tube.

In testimony whereof we hereunto afiix our signatures.

ALBERT PAUL IIANSGERD NICKEL JOIIANNE S JOACHIM SPANNER. 

